The goal of this research is to understand how the expression of mature olfactory system function is influenced by sensory input during ontogeny. Specifically, the proposed research is an investigation of the effects of early unilateral olfactory deprivation on olfactory bulb physiology and function. While early unilateral olfactory deprivation has been shown to produce profound changes in olfactory bulb anatomy, the functional consequences of this deprivation are not known. The proposed research will examine several functional measures under a variety of deprivation conditions. First, response patterns of bulb output neurons, mitral/tufted cells, to odors will be examined after varying durations of deprivation. Second, the effects of deprivation on the activity of bulb interneurons will be assayed using paired-pulse stimulation. Third, the role of glomerular layer dopamine, which is severely reduced by deprivation, will be examined. Fourth, behavior odor detection thresholds following deprivation will be determined. Finally, the age sensitivity and reversibility of deprivation effects on these measures will be determined.